Means for tensioning metallic material in cold reducing mills



- Nov. 24, 1942. EJD. SPANGLER 2,303,143 V MEANS FOR TENSIONING'METALLICMATERIAL'IN COLD REDUCING MILLS Filed Mayl5, 1941 hwnfor.

, Patented Nov. 24, 1942 MEANS FOR TENSIONING METALLIC MATE- RIAL INCOLD REDUCING MILLS Earl D. Spangler, Gary, Ind.

Application'May 15, 1941, Serial No. 393,622

2 Claims.

bite of the rolls and, in general, to bring about a more satisfactoryrolling condition. In tandem mills,usually comprising three to five rollstands arranged in line, the difficulties of providing suitable meansfor tensioning strip being reduced through all of the stands are greatlyincreased to the point where tension is applied only partially, ifapplied at all.

At the present time there are many types of tensioning equipment in use,most of which are grouped into two general categories:

First, those which provide for the retardation of the pay-off reel sothat the material is tensioned between the latter and the takeup reelthrough the roll pass; and Second, those which, by means of clamps,shoes, or drags, resist the advancement of the stock into the roll passto tension the same.

The first group of tensioning devices usually involves rather expensive,elaborate equipment which is not well suited to all cold strip mills,and is subject to the further limitation of being applicable only in thereduction of 'stock of sufficient length to be coiled, and capable ofextending for a substantial part of the rolling operation from thepay-off to the takeup reel.

The second class of devices is for the most part, applicable to any typeof cold rolling mill in present day use, whether originally designed fortensioning or not, since the drags or clamps can be added to theexisting equipment without much difiiculty. These latter, however, havebeen subject to certain disadvantages, including the rapid wearing awayof the clamp shoes, the necessity for frequent replacement, and the notinfrequent uneven wearing away of such shoes or bearings, so as to pulland wrinkle the material entering the mill to a harmful degree. Anotherdisadvantage of the latter class of tensioning devices lies in thefactthat they. are disposed directly in the line of the pass, obstructingthe view of the operator and having such limited movement as to be inthe way during threading up operations. Furthermore, for the most part,the

position of these devices away from the mill is sufiiciently removedfrom the pass of the mill as to make their use in the rolling of thesheets, or other relatively short lengths of metal stock, impracticable.

A serious objection to both classes of tensioning devices as heretoforeconstructed arises from the fact that they must be disposed such adistance from the work r'olls as to render the tensioning of substantiallengths of the trailing ends of coils of strip impossible nearing theconclusion of each rolling operation. Thus, the ends of strip extendingfrom the tension device to the roll pass (usually a dozen feet or so)are rolled under different conditions (without benefit of tension) thanthe remainder of the strip, consequently requiring the scrapping of thisamount of each coil due to departure from gage, surface defects, etc. Intandem mills where a speed differential between pay-oft and takeup reelsis relied upon to create the desired tension, a length of stripcorresponding tothe distance between these reels is produced at the endof each coil rolled which, in the larger mills, would equal nearly feetof strip at the end of each coil that would have to be scrapped.

In the present invention, there is provided a tensioning means for coldreducing mills wherein all of the above named disadvantages have beeneliminated, thereby providing an improved finished product.

Accordingly, it is one of the objects of the present invention toprovide a tensioning means which may be readily applied to any of theordinary types of mills nowin use, which can be used not only fortensioning long lengths of stock, but which also may be used in thereduction of sheets. and other short lengths of stock while at the sametime being in the way of the operator neither during the rollingoperation nor during the threading up period.

It is another object of the invention to provide atensioning means whichis simple and inexpensive in its construction and, yet, a means whichoperates efliciently and effectively to main-,

tain, under tension, those portions of strip or sheets being rolled thatare engaged by the work rolls of a mill down to, and including, thetrailing end extremities thereof.

Various other objects and advantages of this invention will become moreapparent during the course of the following specification and will beparticularly pointed out in the appended claims.

In the accompanying drawing there is shown,

Referring more particularly to the drawing, the

improvedtensioning means of my invention is shown incorporated with a4-high cold reducing? rolling millwhich comprises generally a frame 2, apair of oppositely disposed work rolls 3 and backing up rolls 4. Thestrip to be reduced is introduced between the work rolls 3 and deliveredto a takeup reel 5 arranged on the delivery side of the mill in a mannerwell known to those skilled in the art. It will be understood that thatportion of the strip S on the delivery side of the mill is maintainedunder tension at all times by means of the takeup reel 5.

According to the present invention, there is arranged on a suitablesupport on the entry side of the mill and disposed preferably below thepass line of the strip therethrough, preferably a pair of angularlydisposed fluid pressure cylinders 6 preferably operated by compressedair, with each having a piston I and piston rod 8 which extends from theupper end thereof. There is mounted on the outer ends of the piston rods8 and extending therebetween a shoe or drag member 9 which is preferablyconstructed of wood, but may be constructed of any ,other suitablematerial, and which is ada'ptedto be moved toward and away from theupper work roll -2 by the action of the fluid pressure cylinders 6. Thecylinders 6 are actuated by a source of fluid pressure (not shown) whichis adapted to be introduced from the source of supply through a pipeline .10, into and'through the reversing valve l2 and through the pipesi3 into the cylinders, so as to either move.the shoe upwardly intoengagement withtthe strip and upper roll, or to movethe shoe tlo aretracted position below the path ofgthe strip, as shown in the brokenlines of Figure 1. that that portion of the strip S" on the entry sideof the mill is normally not under tension in the practice of the presentinvention and the stri will normally hang slack, as shown in the brokenlines of Figure l.

The tensioning means of my invention functions in the following manner.When threading up the mill, the valve I2 is actuated so that fluidpressure is introduced into the upperend of the cylinders 8 through thelines l3 whereby the piston rods 8, together with the shoe 9 carriedthereby, are withdrawn away from thestrip to a retracted positiontherebelow, as shown in the broken lines of Figure 1, with such positionbeing below the path or pass.line of the strip between the rolls 3 andthrough the mill so as to enable the operator to properly thread thematerial through the mill. After the mill has been threaded andoperating conditions achieved with the leading end of the strip beingwound on the takeup reel 5, so that the portion of the strip 3' on thedelivery side of the mill is under tension, the valve 9 is actuated soas to relieve the pressure at the upper end of the cylinders 8 andsimultaneously to introduce fluid pressure into It will be understoodthe cylinders, at the opposite or lower ends thereof, so that the pistonrods 8, together with the drag shoe-9 carried thereby will be movedupwardly against the bottom of the strip so as to move the same againtsthe upper work roll 3, as shown in the full lines of Figure 1. It willbe understood that sufficient pressure is introduced into the bottom ofthe cylinder 6 so that the strip is confined under substantialcompressive force at point A between the shoe 9 and the upper work roll.

'It will be understood that it is the purpose of the drag shoe 9 toimpose a drag on that portion of the strip S' on the entry side of themill which is approaching the mill in a slack condition. It will thus'be seen that this places that portion of the strip between point A andpoint B, the bite of the work rolls 3, under tension and that tension ismaintained between the bite of the rolls and across the span of thereduced strip S to the takeup reel 5 which exerts a constant pullthereon. The portion of the strip between the points A and B ismaintained undertension while the metallic material is passingcontinuously between the work rolls 3 due to the fact that the componentof friction existing between the bottom surface of the strip and thedrag shoe 9 is greater than the frictional component prevailing; betweenthe upper surface of the strip and the work roll 2, since the latterconstitutes a metal-to-metal contact, while the former is ametal-to-fibre contact. That is to-say, the coefflcient of frictionbetween wood and metal is greater than that between metal and metalwhere the two metal surfaces tend to move in unison in the samedirection ,while the fibre surface remains stationary relative to themoving metal surface of the strip. Therefore, a frictional drag isobtained at point A so as to place the strip under tension. The actionof the drag member 8 is similar in effect to forcing a wedge between onesurface of the strip in the bite of the rolls and oneof the rollsitself.

v Apart from the tensioning function performed by my device as describedabove, it will be seen that by the use thereof there is providedsufflcient tension in the strip immediately before the same entersbetween the work rolls so as to prevent the strip from piling up ordoubling over and resulting in socalled pinchers" in the strip, which isobjectionable in that such "pinchers" oftentimes damage the work rollsand consequently necessitate the replacement thereof. The drag shoe 9 ofmy invention will not only eliminate the occurrence of the abovereferred to "pinchers but also possesses all of the advantages of atensioning means for accomplishing the purposes for which such means areprovided as hereinbefore set forth.

While in the present instance, the drag shoe 9 is shown positioned belowthe strip and coopcrating with the upper work roll, it will be seen thatthe reverse of this arrangement could be adopted if desired, whereby thedrag bar or shoe, together with its actuating mechanism would be mountedabove the strip with the drag shoethen cooperating with the lower workroll.

It will be observed that because the tension afforded by the presentinvention is applied so close to the reducing zone of the work rolls(never exceeding a distance corresponding to the radius of the workrolls), it may be applied in the reduction of short lengths of material,such as individual sheets, as well as to relatively continuous lengthsof stock similar to strip. In this regard, it will be appreciated thatthe invention is applicable to single stand mills (one of my devicesbeing used at each side of such a mill if it be a reversing mill) and totandem mills, in which case, the invention wouldpreferably be applied toeach of the stands thereof. apparent that whether the tensioningapparatus is disposed above or below the pass line of the mill, it willhave sufficient operating range and such simplicity of construction asto be withdrawable completely from the path of travel of the strip andfrom the pass line of the mill, so as to be out of the line of vision ofthe operator, and to aiford plenty of room in which to work.

It will also be understood that any suitable means for forcefullypropelling and holding the shoe against the strip may be utilizedwithout departing from the spirit of the invention, as, for instance,reverse screw jacks could be substituted for the fluid pressure meansdisclosed herein for illustrative purposes only. One advantage of theluid pressure operating means for controlling the movement of the shoe,particularly where the fluid pressure is supplied from a common source,is that it has a tendency to equalize and, thus, to cause the shoe tobear upon the strip uniformly across the width of the I latter. Wherescrew jacks, or other mechanical means, are provided, the shoe may bepivoted or swiveled to the actuating rods 6 (which-might be only one innumber, disposed centrally of the shoe) so that the latter may have someflexibility of movement in accommodating itself to the It will also be-I claim:

1. Apparatus of the class described including, in combination, a pair ofoppositely disposed cold reducing work rolls between which metallicmaterial is adapted to pass so as to efiect a reduction in the thicknessthereof, and a longitudinally extending drag shoe made of a fibroussubstance arranged substantially parallel to the axes of said rolls onthe entrance side thereof and immediately in front of the same, andreciprocable means for moving and supporting said drag shoe, saidreciprocable means in one position adapted to project said shoe acrossthe path of the material entering between the rolls so as to force thematerial into engagement with one of said rolls at a spaced distancefrom the bite of said rolls whereby that portion of the material betweensaid shoe and the bite of the rolls is placed under tension as thematerial passes continuously between the rolls.

2. Apparatus of the class described including,

. in combination, a pair of oppositely disposed cold tion away from saidroll.

reducing work rolls between which metallic material is adapted to passso as to effect a reduction in the thickness thereof, a drag shoearranged on the entrance side of said work rolls immediately" in frontthereof at a point to one side of the strip material for pressing saidmaterial securely against one of said work rolls while the material ismoving between the rolls with the coefllcient friction of the drag shoeagainst the EARL D. SPANGLER.

